active

Transmission channels for light in absorbing random media: from diffusive to ballistic-like transport
S. F. Liew, S. M. Popoff, A. P. Mosk, W. L. Vos, and H. Cao
Phys. Rev. B 89, 224202: 1-10 (2014)

Classification of light sources and their interaction with active and passive environments
R. G. S. El-Dardiry, S. Faez, and A. Lagendijk
Phys. Rev. A 83, 031801(R) (2011)